If you'd gotten someone to refer you for the card, you'd have received 22,000 Membership Reward points which transfers to at least 22,000 Avios - there's been transfer bonuses on top of this in the past. You wouldn't have got the £35 though, but the 22K Avios is worth a lot more than that.

It depends on your situation and what you'll use them for.

I'd start at a base of 0.75 - 1p, depending on whether you plan to use them for full redemptions or upgrades. If you think you'll use them with the BA Amex 241 voucher, then I'd value them nearer the 1 - 1.25p each.

But, it depends on your target routes and class of travel. Do some dummy bookings and see what you'd save.